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Biomedical subjects

R A Hinder

Publications and source records attributed to R A Hinder.

At least 145 records · Page 8Linked to original sources
PubMed1988

Intrathecal papaverine for the prevention of paraplegia after operation on the thoracic or thoracoabdominal aorta.

Eleven patients undergoing operation on the descending or thoracoabdominal aorta were administered papaverine intrathecally in an attempt to protect the spinal cord from ischemic damage. Concurrently, 19 patients, also undergoing operation on the thoracic or thoracoabdominal aorta, were operated on with a variety of conventional techniques, including distal aortic perfusion, but were not given intrathecal papaverine. No signs of early neurologic injury developed in any of the patients in the intrathecal papaverine group, although delayed paraparesis developed in one of the patients (9%; 70% confidence limits = 1% to 28%). On the other hand, eight of 19 patients undergoing operation with conventional techniques had either lower extremity paraparesis or paraplegia postoperatively (42%; 70% confidence limits = 29% to 57%; p = 0.058). Intrathecal papaverine appeared to provide spinal cord protection during thoracic aortic operations, particularly during prolonged periods of aortic cross-clamping. Papaverine was not associated with increased risk and may be superior to other conventionally used modalities. We conclude that continued evaluation of this technique is justified.

Adult↗
PubMed1988

Management of gastric emptying disorders following the Roux-en-Y procedure.

In 46 patients with gastric resection and Roux-en-Y gastrojejunostomy, gastric emptying was studied with the gamma camera. Seventeen patients were free of symptoms, 11 vomited occasionally (less than 5 times weekly), and 18 were severely incapacitated with daily vomiting, weight loss, and bezoar formation. Patients with occasional vomiting had early rapid emptying similar to that seen in the patients who were without symptoms and responded satisfactorily to nonsurgical therapy. The 18 patients with severe vomiting showed a marked delay in the emptying of the solid meal (p less than 0.01) but normal emptying of the liquid. There was no difference between those with and those without stomal ulceration or stomal stenosis. The stasis occurred in the stomach and not in the Roux limb. All 18 patients had a further extensive gastric resection, leaving a 50 to 75 ml upper gastric remnant drained by Roux-en-Y gastroenterostomy. Fifteen of these patients showed improvement and gained weight, and the gastric emptying of both the solid and liquid test meals is now faster than in any of the other groups (p less than 0.03). We conclude that extensive gastric resection is an effective means to reduce symptoms and improve gastric emptying in selected patients with severe gastric stasis of solid food after the Roux-en-Y procedure.

Anastomosis, Roux-en-Y↗
PubMed1987

Prevention of gastric mucosal lesions following aortic cross-clamping.

Stress ulceration is frequently encountered after cardiovascular surgery. In this study of 32 male baboons, severe gastric ischaemia was used to produce gastric stress lesions. The occurrence of these lesions was reduced by allopurinol (P = 0.03) and completely prevented by the combination of allopurinol with superoxide dismutase (P = 0.004). A shorter ischaemic period also reduced the number of lesions (P = 0.02). Concurrent with the stress lesion formation, there was a fall in mucosal glutathione and oxidized glutathione levels (P less than 0.05).

Allopurinol↗
PubMed1987

Is there a relationship between gastric mucosal blood flow and stress lesions in hemorrhagic shock?

The relationship between gastric mucosal blood flow and stress lesion formation during hemorrhagic shock was studied in anesthetized dogs. Shock was induced by graded arterial bleeding. Blood flow was measured by means of the radioactive microsphere technique. Mapping of blood flow was achieved by measuring the microsphere accumulation in mucosal and muscle segments of 1-2 cm side length of the entire stomach. To produce a varying incidence of lesions the metabolic acidosis of shock was either fully corrected by intravenous sodium bicarbonate (n = 5), partially corrected (n = 4) or left uncorrected (n = 3). Mucosal lesions developed more frequently in dogs without correction than in dogs with partial correction or full correction. In 4 dogs not subjected to shock, no mucosal lesions were observed at the end of the experiments. Mucosal blood flow varied from segment to segment by a factor of up to 20, but individual segments tended to maintain their relative flow values during shock. Correction of metabolic acidosis did not significantly affect blood flow. Likewise, flow was similar in segments with and without lesions. Therefore, low regional blood flow did not predispose to the development of lesions and high flow did not prevent them. We conclude that focal mucosal ischemia alone does not lead to stress lesion formation during hemorrhagic shock.

Animals↗
PubMed1986

The pathophysiology of gastric electrical activity and emptying.

A good understanding of upper gastrointestinal physiology is required to properly understand the pathophysiological events in various diseases or after operations on the upper gastrointestinal tract. It is evident that the electrical activity in infancy does not have the orderly pattern of that in adults and that severe disorder of this activity may produce abnormalities of gastric emptying. Surgical procedures on the gastrointestinal tract can cause alterations in the electrical and motility patterns of the stomach. The influence of various surgical manoeuvres on upper gastrointestinal motility indicates that the mere destruction of the pylorus does not in itself produce a gross distortion of the emptying of liquids or solids from the stomach, but that only when a vagotomy or antrectomy is added, do we find rapid gastric emptying of liquids and incontinence of solids. The effect of this, coupled with rapid small bowel transit, may be responsible for the nutritional disturbances sometimes seen after vagotomy or gastrectomy. These phenomena may partly account for some of the symptoms of the dumping syndrome. The gastric incontinence seen after distal gastrectomy can be corrected by the interposition of jejunal loops, but the direction of peristalsis within these loops is immaterial in that both iso- and retro-peristaltic loops are able to correct the disordered emptying pattern. Clinicians should not take for granted that which might seem obvious after gastric surgical procedures without careful testing and evaluation both in experimental animals and where possible in man. Failing this, incorrect clinical and therapeutic decisions might be taken.

Adult↗
PubMed1986

Cross-clamping of the thoracic aorta. Influence of aortic shunts, laminectomy, papaverine, calcium channel blocker, allopurinol, and superoxide dismutase on spinal cord blood flow and paraplegia in baboons.

There is a high incidence of paraplegia associated with thoracic aortic cross-clamping, even when cardiopulmonary bypass or shunts are used. In 56 adult baboons, spinal cord blood flow (SCBF), vascular anatomy, and paraplegia rates were evaluated. Tissue blood flow was measured by radioactive microspheres. Various procedures were used to increase SCBF and to prevent ischemia-reperfusion injury. It was found that the rate of paraplegia was inversely correlated with neural tissue ischemia (SCBF) and directly correlated with reperfusion hyperemia. Two methods completely prevented paraplegia. These two methods were a thoracic shunt with occlusion of the infrarenal aorta or cerebrospinal fluid drainage plus intrathecal papaverine injection, both of which were associated with an increased SCBF. Furthermore, papaverine dilated the anterior spinal artery (ASA) (p = 0.007) and increased the blood flow through the lower ASA. Whereas procedures utilizing a calcium channel blocker (flunarizine), allopurinol, superoxide dismutase (SOD), laminectomy alone, and a thoracoabdominal shunt not perfusing the arteria radicularis magna (ARM) all failed to prevent paraplegia, allopurinol (p = 0.026) and SOD (p = 0.004) did prevent gastric stress lesions, indicating that their failure to prevent paraplegia was not due to a lack of activity. Of great clinical interest is that, if a shunt is used and the ARM is perfused, infrarenal aortic cross-clamping increases SCBF, thus preventing paraplegia. Intrathecal application of papaverine proved to be even more effective in increasing SCBF and also completely prevented paraplegia. As this is a safer procedure than the insertion of shunts, this is the method of choice for the prevention of paraplegia associated with thoracic aortic cross-clamping. The preliminary trial using intrathecal papaverine in human beings has thus far shown no adverse side effects from the drug, and no paraplegia has occurred.

Allopurinol↗
PubMed1986

Peptic ulceration--what can be expected from animal models.

Chronic peptic ulceration remains a disease which predominantly affects man. Great difficulty has been experienced in producing chronic mucosal ulcers in animals; however, there are many effective animal models for acute peptic ulceration. These can be used to test theories on the pathogenesis and prevention of mucosal ulceration and the effect of medical and surgical procedures used to treat ulcer disease. In addition, the mode of action, side effects, and comparative efficacy of drugs can be tested. Techniques that have been used in the laboratory to produce ulceration include surgical alterations of the upper gastrointestinal tract, mechanical trauma, the mucosal application of noxious agents, the exogenous and endogenous stimulation of acid secretion, or the application of stress. Great care must be exercised in extrapolating from these results, since different species show varying responses. Areas that have been studied include mucosal blood flow, acid/base balance, mucosal pH, hormones, mucosal resistance, the protective properties of mucus, ultrastructure, microvasculature, biochemical changes, oxygen-derived free radicals, the influence of the nervous system, and the ability to resist luminal noxious agents under different conditions. The most fruitful area for the future investigation of chronic peptic ulceration will remain in the clinical sphere, but valuable information can still be gained concerning the mechanisms of production and therapy of peptic ulcers by using animal models under defined laboratory conditions.

Animals↗
PubMed1986

Relationship of spinal cord blood flow to vascular anatomy during thoracic aortic cross-clamping and shunting.

No satisfactory explanation exists as to why paraplegia occurs despite distal aortic perfusion during thoracic aortic operations. We studied the hemodynamics, paraplegia rate, and spinal cord blood flow with radioactive microspheres in 17 male adult baboons, with particular reference to the arteria radicularis magna. The groups consisted of control animals, subjected to cross-clamping for 60 minutes, and animals with aorto-aortic shunts operational for 60 minutes. There were no significant left ventricular hemodynamic advantages with shunting. Shunting significantly increased lumbar spinal cord blood flow (p = 0.0009), which correlated with the distal aortic mean pressure (r = 0.59, p = 0.008). However, lower thoracic spinal cord blood flow did not increase during shunting (p = 0.2) and did not correlate with the distal aortic pressure (r = 0.11, p = 0.64). This is due to the vascular anatomy of the anterior spinal artery, which was, as in man, smaller above (0.278 mm) than below (0.744 mm) the entry of the arteria radicularis magna. Resistance to flow, as calculated by Poiseuille's equation, was 51.7 times greater up the anterior spinal artery as compared with down this artery. The vascular anatomy explains the absence of paraplegia in one baboon in the cross-clamp group and paraplegia in one baboon in the shunt group. Thus, distal aortic perfusion protects the spinal cord below the arteria radicularis magna but not above it.

Animals↗
PubMed1985

Prophylactic antimicrobials in elective colorectal and biliary surgery.

In 97 patients undergoing elective biliary (44) or colorectal (53) surgery, cases were randomly allocated to receive peri-operative prophylaxis with either cefoxitin (Mefoxin; MSD) or metronidazole, penicillin and tobramycin (MPT). Sepsis occurred in 3 of the biliary cases (6,8%) and in 16 of the colorectal cases (30,2%). In the colorectal group sepsis occurred equally in patients receiving cefoxitin (22,2%) or MPT (38,5%) (P = 0,20). Patients who developed sepsis did not have a prolonged hospital stay; strict criteria were used to define sepsis in this study and this explains the apparently high sepsis rate. A positive wound culture at the end of the operation was more common after colorectal surgery (30,2%) than after biliary surgery (4,6%) and was associated with a higher subsequent infection rate (P = 0,02).

Aged↗
PubMed1985

Distribution of intraventricular salmon calcitonin and suppression of gastric secretion.

Intracerebroventricularly (ICV) administered [125I] salmon calcitonin (sCT) was rapidly transported to the blood, but the permeability of the blood-brain barrier to sCT was low. ICV injected intact [125I]sCT was predominantly deposited in the periventricular mesencephalon and in the kidneys, and intravenously (IV) injected [125I]sCT in the kidneys, respectively. After both ICV and IV administration [125I]sCT was not retained by the stomach in large amounts. ICV and subcutaneously (SC) injected sCT caused suppression of gastric secretion volume, and of acid and pepsin outputs; the potency ratios between half maximal inhibitory amounts of sCT administered SC and ICV were 161, 252 and 13, respectively. On the other hand, perfusion of isolated whole mouse stomachs with sCT did not affect basal or stimulated acid and pepsin secretion. These findings indicate that sCT inhibits gastric acid secretion via receptors localized in the hypothalamus and in adjacent areas of the brain.

Animals↗